I currently have a sorority of 6 in an approximately 15-gallon NPT. The tank is on the very tail end of cycling and the plants have grown wonderfully since I introduced them about a month ago. The girls are just lovely: four are siblings, and the other two petstore ladies are the co-alphas of the pack.

Recently, one of the siblings, Hope, had a jumping accident and was out of the tank for almost half an hour before we found her. Fortunately, she recovered extremely well; however, the bits of her fins that had dried out eventually fell off, and I believe she developed an infection, leading to minor fin rot. Additionally, one of the other siblings-- Leroux, the 'omega'-- got a few nips from a more senior tankmate and seems to have caught the rot as well.

I've isolated the two girls in hospital bowls; despite the fact that there are only four girls remaining in the tank, they don't seem to be displaying any excess aggression. The tank is pretty big and densely-planted, and they all seem quite comfortable.

However, the two isolated girls have become extremely stressed outside of the tank. They've been with their siblings almost their entire lives-- they're only about seven months old now-- and they've both started displaying stress stripes and refusing food. (Before being removed from the tank, both girls were ravenous eaters and extremely perky aside from their fins.)

The omega, Leroux, also appears to be very skinny and has stringy poop, which leads me to believe she might have an internal parasite-- I'm going to attempt treating her with medication today.

Is there anything I can do to make the isolated girls more comfortable? I'm expecting a shipment of IALs from the BBC soon, but I don't know if they'll get here soon enough. Additionally, is there any risk in keeping only four girls in the tank at one time? They all seem pretty comfortable, but I've known the head alpha to be very aggressive at times.